simple SQL Pivot Query - sql-server

Question

I apologize for my ignorance. I just am not familiar with pivot queries AT ALL and all the examples I find seem about as clear as mud. I have table that returns GroupName and ID Numbers.
For Example:
SELECT GroupName, IDnumber FROM do.Table_1
Returns
GroupName IDnumber
1 8395
1 A660
1 8396
1 A661
2 8398
2 A662
2 8399
What I want is something more like this:
GroupName ID1 ID2 ID3 ID4
1 8395 A660 8396 A661
2 8398 A662 8399 NULL
How can I do this? Pivot query? Some other method?
I am open to suggestion and appreciate any help you could provide.

Answer 1

Yes, you can do it using PIVOT but not in this shape, you have firstly to generate a row number to use it to format the data in the way you want. Something like this:
WITH Ranked
AS
(
SELECT GroupName, IDnumber,
ROW_NUMBER() OVER(PARTITION BY GroupName ORDER BY GroupName) AS RN
FROM Table1
)
SELECT GroupName,
[1] AS ID1, [2] AS ID2, [3] AS ID3, [4] AS ID4
FROM Ranked AS r
PIVOT
(
MAX(IDnumber)
FOR RN IN([1], [2], [3], [4])
) AS p;
SQL Fiddle Demo
This will give you:
| GROUPNAME | ID1 | ID2 | ID3 | ID4 |
|-----------|------|------|------|--------|
| 1 | 8395 | A660 | 8396 | A661 |
| 2 | 8398 | A662 | 8399 | (null) |
If you want to do it dynamically and not to write the row number by hand in the pivot table operator, you have to do it using dynamic SQL, something like:
DECLARE #cols AS NVARCHAR(MAX);
DECLARE #colnames AS NVARCHAR(MAX);
DECLARE #query AS NVARCHAR(MAX);
SELECT #cols = STUFF((SELECT distinct ',' +
QUOTENAME(RN)
FROM
(
SELECT ROW_NUMBER() OVER(PARTITION BY GroupName ORDER BY GroupName) AS RN
FROM Table1
) AS t
FOR XML PATH(''), TYPE
).value('.', 'NVARCHAR(MAX)')
, 1, 1, '');
SELECT #colnames = STUFF((SELECT distinct ',' +
QUOTENAME(RN) + 'AS' +
QUOTENAME('ID' + CAST(RN AS NVARCHAR(5)))
FROM
(
SELECT ROW_NUMBER() OVER(PARTITION BY GroupName ORDER BY GroupName) AS RN
FROM Table1
) AS t
FOR XML PATH(''), TYPE
).value('.', 'NVARCHAR(MAX)')
, 1, 1, '');
SELECT #query = 'WITH Ranked
AS
(
SELECT GroupName, IDnumber,
ROW_NUMBER() OVER(PARTITION BY GroupName ORDER BY GroupName) AS RN
FROM Table1
)
SELECT GroupName, ' + #colnames +
' FROM Ranked AS r
PIVOT
(
MAX(IDnumber)
FOR RN IN(' + #cols + ')' +
') p';
execute(#query);
SQL Fiddle Demo
This should give you the same result:
| GROUPNAME | ID1 | ID2 | ID3 | ID4 |
|-----------|------|------|------|--------|
| 1 | 8395 | A660 | 8396 | A661 |
| 2 | 8398 | A662 | 8399 | (null) |

Answer 2

You may need to use dynamic pivoting since the Id will be dynamic. Here is your sample table
SELECT * INTO #TEMP
FROM
(
SELECT 1 GroupName, '8395' IDnumber
UNION ALL
SELECT 1, 'A660'
UNION ALL
SELECT 1, '8396'
UNION ALL
SELECT 1, 'A661'
UNION ALL
SELECT 2, '8398'
UNION ALL
SELECT 2, 'A662'
UNION ALL
SELECT 2, '8399'
)TAB
Select row number over each Groupname and insert into a temporary table so that it can be used for both selecting the columns for pivoting and inside the pivot
SELECT *,
'ID' + CAST(ROW_NUMBER() OVER(PARTITION BY GroupName ORDER BY GROUPNAME) AS VARCHAR(10)) IDS
INTO #NEWTABLE
FROM #TEMP
Select columns for pivot
DECLARE #cols NVARCHAR (MAX)
SELECT #cols = COALESCE (#cols + ',[' + IDS + ']',
'[' + IDS + ']')
FROM (SELECT DISTINCT IDS FROM #NEWTABLE) PV
ORDER BY IDS
Now pivot dynamically
DECLARE #query NVARCHAR(MAX)
SET #query = '
SELECT * FROM
(
SELECT * FROM #NEWTABLE
) x
PIVOT
(
MAX(IDnumber)
FOR IDS IN (' + #cols + ')
) p
'
EXEC SP_EXECUTESQL #query
Click here to view the result (incase an error is occured on loading page press RUNSQL, it works)
RESULT